Strange, Wonderful Things Occur in Monolayered Materials

Strange and wonderful things happen in materials just one atom thick.

Kin Fai Mak is spending the week at Case Western Reserve University discussing his pioneering use of spectroscopy—the interaction of matter and light—to probe this two-dimensional world. His talks focus on how single layers of common materials, such as graphite, which enables electrons to act as if they have no mass and to travel at 620 miles per hour; and how the materials may harbor properties that could be harnessed for next-generation transistors, computer memory and more.

Mak, an experimental condensed matter physicist and postdoctoral fellow at Cornell University’s Kavli Institute for Nanoscale Science, is the winner of the 2012 Michelson Postdoctoral Prize, the 16th recipient of this award. The Case Western Reserve physics department awards the prize annually to an outstanding young scholar in any field of physics.

In addition to giving technical presentations aimed at physicists, electrical engineers and materials scientists, Mak will deliver a Michelson colloquium, geared for undergraduates and a general audience.

Describing the practical side of his studies, Mak said, “The research community is looking into other possible applications for graphene and other new materials that provide better device function, better than silicon.”

Electrons move faster through the lattice-like structure of graphene, which is a single layer of graphite, than any other material. Which is why the material is now the focus of intense research in electronics – for faster-still computer transistors and other devices currently built with silicon.

Mak, who earned his PhD studying graphene, has branched out, finding that other single-layered materials, such as molybdenum disulfide, also offer promising attributes.

Mak has found that, like graphene, the two-dimensional crystal structure of molybdenum disulfide can act as an insulator inside, yet be highly conductive on the surface, enabling electrons to act as if they have no mass, and, theoretically, make them scatter-proof.

The insulation also gives the electrons a recently discovered degree of freedom not seen in common materials. Called the valley degree of freedom, it may be useful, like the electron spin used in computer hard discs, for computer memory storage.

Graphene oxide membranes have been receiving attention for their extremely powerful separation abilities and the ease at which it can be modified, allowing for membrane permittivity to be fine-tuned. These membranes show the potential to be used for water purification, ‘green’ gas purification and greenhouse gas capture.